Now, to the unraveling of a long, winding and weird custody battle. It's the story of a 24-year-old thought to be missing for decades. Now found, a grown, married man. How did police track him down after all these years? And what happened here? Abc's john muller is on the story. Reporter: Dan, this case was so cold, indiana state police had to reopen it when the stepfather turned over his son's social security card a few months ago. It was that simple piece of information, a social security number, that led investigators to a 24-year-old whose name changed but whose license picture looked a lot like the 5-year-old boy who went missing. This is a lot for me to take in. Reporter:24-year-old richard landers jr. Just received a bombshell. Police say his grandparents, who reportedly raised him nearly all his life, actually abducted him when he was just 5 years old. Until I actually get to walk up and say hello to him again, i don't know that it's going to be real. Reporter: His father, richard landers sr., Is shocked. His mother, apparently was jumping for joy, when she learned her little boy was out there, alive and well, now married, and expecting a child of his own. Landers incredible story started two decades ago, after his parents went through a bitter divorce. His mother, reportedly living in a car. Police say his paternal grandparents unhappy with the custody proceedings, took him from his home in wolcotville, indiana, brought him to minnesota. All three changed their names. But forgot richard's social security number. That's how police finally tracked him down. Young man living in the state of minnesota, was using that social security number. Doing further checking on who this person was, he had the same date of birth. Reporter: Authorities traced the number to this property in minnesota, where richard landers jr. Was living as michael jeff landers. Police say there were no signs he was ever abused. The grandparents were charged in 1999 with interference of custody. Since so much time had passed, the charges were eventually dropped. No word on if new charges will be filed. Strange case.

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